The production of man-made fibers has long used spunbonding techniques to produce fibers for use in forming nonwoven webs of a material. FIGS. 1A and 1B illustrate prior art machines which manufacture nonwoven webs using spunbonding techniques.
FIG. 1A illustrates a prior art apparatus 10 for producing spunbond fibers. The spunbond apparatus typically contains a fiber draw unit 12 positioned above an endless belt 20 which is supported on rollers 22. FIG. 1B illustrates general schematics of the inside portions of fiber draw unit 12 taken along lines 1B in FIG. 1A. Fiber draw unit 12 includes a longitudinal air chamber which contains an upper portion 14, a mid-portion 16, and a lower portion or tail pipe 18. The fiber draw unit also includes a first air plenum 30 and an air nozzle represented by reference numeral 32 leading from the first air plenum 30 to mid-portion 16 of the fiber draw unit 12. Additionally, a second air plenum 34 also communicates with mid-portion 16 of the fiber draw unit 12 via an additional air nozzle represented by reference numeral 36. The spunbond apparatus 10 also includes equipment 38 known in the art for melting and extruding polymer resin through dies to create fibers 40. Typically, this equipment feeds resin fed from a supply to a hopper extruder, through a filter, and finally through a die to create the fibers 40. The fibers are quenched by cool air entering the fiber draw unit 12 through upper air quench ducts 46 and 48.
High velocity air is admitted into the fiber draw unit 12 through plenums 30 and 34 via air inlets 42 and 44, respectively. The addition of air to the fiber draw unit 12 through nozzles 32 and 36 aspirates air from above the fiber draw unit through upper air quench ducts 46 and 48. The air and fibers then exit through tail pipe 18 into exit area 50. Generally, air admitted into the fiber draw unit 12 draws fibers 40 as they pass through the fiber draw unit. The drawn fibers are then laid down on endless belt 20 to form a non-woven web 52 as is seen in FIG. 1A. Rollers 54 may then remove the non-woven web from the endless belt 20 and further press the entangled fibers together to assist in forming the web. The web 52 is then typically bonded to form the finished material. Spunbond nonwoven fabrics are generally bonded in some manner as they are produced in order to give them sufficient structural integrity to withstand the rigors of further processing into a finished product. Bonding can be accomplished in a number of ways such as hydroentanglement, embossing by calender and anvil, needling, ultrasonic bonding, adhesive bonding, stitchbonding, through-air bonding, and thermal bonding.
It is an object of the present invention to provide novel air nozzles for directing air into a fiber draw unit. It is a further object of this invention to provide novel nozzle geometries that provide improved, desirable air flow into the fiber draw unit, which in turn affects the characteristics of the drawn fibers.
It is a further object of the present invention to provide a novel adjustable nozzle that allows varying the size of a nozzle outlet. It is yet another object of this invention to provide an adjustable nozzle having less deflection due to air pressure through the nozzle.